A growing movement to remove laws against women going topless is headed to court in Colorado.

A federal lawsuit filed Tuesday challenges Fort Collins' indecency code, which makes it a crime for women but not men to show their nipples.

The Fort Collins City Council voted unanimously last year to keep a law that prohibits the display of female breasts, rejecting a growing movement to remove gender-specific indecency codes.

The hometown of Colorado State University did make an exception for nursing mothers. But otherwise it remains a $250 fine for a woman over the age of 10 to display her breast "below the top of the nipple."

Two women suing Fort Collins say the law is sexist. The say it "treats women differently than men by subjecting them to inferior legal status and criminalizing their expression based on their sex."

They seek an injunction against the law.

Other cities, including Denver, Vail, Colorado, and New York, have removed gender-specific language in their indecency codes. Indecency codes are largely local, with very few states having laws on the books banning the exposure of female breasts.

A federal judge in Chicago recently ruled against a woman challenging that city's law against women displaying nipples. The woman fought a $150 fine tor participating in a 2014 "Go Topless Day" protest near Lake Michigan.

Gender-specific indecency laws have gotten increased attention in recent years. A 2014 film "Free The Nipple" explored the topic, and celebrities including Rihanna and Miley Cyrus have clashed with social media sites for censoring photos showing their nipples, while not removing photos of topless men.